1. Field of the Invention
This invention relates to an information recording method. This invention particularly relates to a method for recording information on an information recording medium, which is provided with a semiconductor layer and a layer of a ferroelectric substance, by means of directions of polarization of the ferroelectric substance.
2. Description of the Prior Art
Information recording media, on which various kinds of information, such as image signals and audio signals, can be recorded at a high density or which can be used as high-density signal memories for computers, have been proposed in, for example, Japanese Unexamined Patent Publication No. 57(1982)-27447. The proposed information recording medium comprises a semiconductor layer and a layer of a ferroelectric substance overlaid on the semiconductor layer and records the information by means of directions of polarization of the ferroelectric substance. Recording of the information on the proposed information recording medium is carried out by moving an electroconductive head (an electrode) on the ferroelectric substance layer, and at the same time applying a voltage to the ferroelectric substance layer such that only predetermined portions of the ferroelectric substance layer may be selectively polarized in a predetermined direction. When the information is to be reproduced from the information recording medium, a change in the electrostatic capacitance of the recording medium due to depletion layers, which are formed in the semiconductor layer by the polarization of the ferroelectric substance, is detected by an electroconductive head.
When information is recorded on the aforesaid information recording medium, the recording speed is determined by the speed, with which the polarization of the ferroelectric substance is reversed. It has heretofore been considered that the speed, with which the polarization of the ferroelectric substance is reversed, will take a value intrinsic to each kind of the ferroelectric substance. This consideration is correct in one aspect. However, research carried out by the inventors revealed that the speed, with which the polarization of the ferroelectric substance is reversed, often varies for the same kind of the ferroelectric substance. If the speed, with which the polarization of the ferroelectric substance is reversed, becomes low, the recording speed will inevitably become low, and the time required for the information to be recorded will become long.